The German Patent reference DE 30 36 050 C2 describes a capacitance system with a dielectric sheet, whereby the sensor exhibits an electrode located on one side of the sheet, which covers the same amount of space as the two electrodes located on the opposite side of the sheet; these two electrodes are shaped such that one encircles the other.
The European Patent reference EP 859 467 B1 describes a sensor device with a capacitance sensor element consisting of conductive foam, which is pressed onto the back side of a panel.
The German Patent reference DE 201 197 00 U1 describes a sensor device, for which an electric conductive layer is provided on the back side of a transparent panel that will be contacted via a contact component.